uart communication problem and microprocessor flash problem

[KTW]

Hi all,

I am trying to flash to flash IC through microprocessor with uart terminal.
My PC connect to USB to Uart converter and try to flash to Flash IC.

My problem is only one board can work and the other boards are not working even though all the connection and setting are the same. I tried to see the signal waveform from Uart pins and found that the data send one time only and stop for those not working boards.

Also, i tried to check with hyperterminal to confirm the Uart communication. It also sometimes not working.

Please help to advise where could the problem come. From hardware connection or software problem?

Thanks for advance.

 

[bokzsamot]

You had described Your problem very indistinctly. What sort of converter do You use? Maybe (very likely) Your converter has on its output RS-232 voltage level. In this case You need another IC (like eg max232) to convert voltage to positive value, passed to Yours devices. But it is only a guess. You should put more info.